UK–(ENEWSPF)–14 March 2013. Neanderthal brains were adapted to allow them to see better and maintain larger bodies, according to new research by the University of Oxford and the Natural History Museum, London.
Although Neanderthals’ brains were similar in size to their contemporary modern human counterparts, fresh analysis of fossil data suggests that their brain structure was rather different. Results imply that larger areas of the Neanderthal brain, compared to the modern human brain, were given over to vision and movement and this left less room for the higher level thinking required to form large social groups.
The analysis was conducted by Eiluned Pearce and Professor Robin Dunbar at the University of Oxford and Professor Chris Stringer at the Natural History Museum, London, and is published in the online version of the journal, Proceedings of the Royal Society B. Looking at data from 27,000–75,000-year-old fossils, mostly from Europe and the Near East, they compared the skulls of 32 anatomically modern humans and 13 Neanderthals to examine brain size and organisation. In a subset of these fossils, they found that Neanderthals had significantly larger eye sockets, and therefore eyes, than modern humans.
The researchers calculated the standard size of fossil brains for body mass and visual processing requirements. Once the differences in body and visual system size are taken into account, the researchers were able to compare how much of the brain was left over for other cognitive functions.
Previous research by the Oxford scientists shows that modern humans living at higher latitudes evolved bigger vision areas in the brain to cope with the low light levels. This latest study builds on that research, suggesting that Neanderthals probably had larger eyes than contemporary humans because they evolved in Europe, whereas contemporary humans had only recently emerged from lower latitude Africa.
‘Since Neanderthals evolved at higher latitudes and also have bigger bodies than modern humans, more of the Neanderthal brain would have been dedicated to vision and body control, leaving less brain to deal with other functions like social networking,’ explains lead author Eiluned Pearce from the Institute of Cognitive and Evolutionary Anthropology at the University of Oxford.
‘Smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments because they would have had fewer friends to help them out in times of need. Overall, differences in brain organisation and social cognition may go a long way towards explaining why Neanderthals went extinct whereas modern humans survived.’
‘The large brains of Neanderthals have been a source of debate from the time of the first fossil discoveries of this group, but getting any real idea of the “quality” of their brains has been very problematic,’ says Professor Chris Stringer, Research Leader in Human Origins at the Natural History Museum and co-author on the paper. ‘Hence discussion has centred on their material culture and supposed way of life as indirect signs of the level of complexity of their brains in comparison with ours.
‘Our study provides a more direct approach by estimating how much of their brain was allocated to cognitive functions, including the regulation of social group size; a smaller size for the latter would have had implications for their level of social complexity and their ability to create, conserve and build on innovations.’
Professor Robin Dunbar observes: ‘Having less brain available to manage the social world has profound implications for the Neanderthals’ ability to maintain extended trading networks, and are likely also to have resulted in less well developed material culture – which, between them, may have left them more exposed than modern humans when facing the ecological challenges of the Ice Ages.’
The relationship between absolute brain size and higher cognitive abilities has long been controversial, and this new study could explain why Neanderthal culture appears less developed than that of early modern humans, for example in relation to symbolism, ornamentation and art.
- Research method used
The researchers calculated the standard size of fossil brains for body mass and visual processing requirements. They did this by using the ratio of living human body mass to fossil body mass to rescale the brains of the Neanderthals and fossil contemporary humans to the body mass of an average living human. They also used the known relationship between the height of the eye socket and the size of visual brain areas in living primates to estimate how much of the brain was dedicated to visual processing in Neanderthals and modern humans. The difference between the two was then subtracted from the Neanderthal brains. This created a set of brains the size they would be if all the fossils had the same body mass as a living human and had the same sized visual brain areas. Once the differences in body and visual system size are taken into account, the researchers were able to compare how much of the brain was left over for other cognitive functions.
The research is funded by the British Academy Centenary Research Project, ‘Lucy to Language: the Archaeology of the Social Brain’ and the Boise Fund, University of Oxford. Lucy to Language: The project aims to explore how the early hominid brain evolved from its essentially apelike beginnings among the earliest australopithecines (ca 3-5 million years ago) to the modern human potential of the “Upper Palaeolithic Revolution” (ca 50,000 years ago) and its final expression in the dramatic social and economic changes of the last 10,000 years. Lucy to Language: The Archaeology of the Social Brain’.
- Professor Robin Dunbar
Professor Robin Dunbar is former Professor of Evolutionary Anthropology and is currently Professor of Evolutionary Psychology at Oxford University. His principal research interest is the evolution of sociality. He was elected a Fellow of the British Academy in 1998. Professor Robin Dunbar and Eiluned Pearce are funded by a European Research Council advanced grant. More information: http://www.neuroscience.ox.ac.uk/directory/robin-i-m-dunbar/
- Professor Chris Stringer
Professor Chris Stringer is a member of the Ancient Human Occupation of Britain Project, funded by the Leverhulme Trust, and his research is supported by the Human Origins Research Fund and the Calleva Foundation.
- The Natural History Museum
The Natural History Museum is an award-winning tourist attraction and also a world-leading science research centre. Through its collections and scientific expertise, the Museum works to help understand and maintain the richness and diversity of our planet, with groundbreaking partnerships in more than 70 countries. For more information go to www.nhm.ac.uk